Abstract
In this study, lettuces, tomatoes, and prince melons were cultivated and watered by the use of the drip irrigation method and the sub-irrigation method by the use of negative pressure difference. These cultivation investigations were carried out in order to compare the relative degrees of difficulty of water management control in the sub-irrigation method and drip irrigation method with regard to water supply, quality and quantity of harvest. The results obtained were as follows.
1) Water wasted in the sub-irrigation method was found to be less than in drip irrigation.
2) In the investigation of lettuce cultivation, water management in the sub-irrigation method was slightly inadequate, resulting in a considerable decrease in water supply compared with the drip irrigation method, and a slight decrease in the quality and quantity. However, water productivity was higher than in the drip irrigation method.
3) In the investigation of tomato cultivation, the quality and quantity of the harvest in the sub-irrigation method were superior and also the water productivity was shown to be higher than in the drip irrigation method.
4) In the investigation of prince melon cultivation, the quality and the quantity of the harvest in the sub-irrigation method were shown to be superior, and also the water productivity to be higher, than in the drip irrgation method.
5) In the sub-irrigation method, as a little water was automatically and successively supplied for 24 hours and water management was achieved only by negative pressure produced in the porous pipe, the sub-irrigation method was considered to be easier than the drip irrigation method with regard to the control of water management.
